Round balers are typically provided with moving belts that compactively envelop the bale as it is being formed and drive the bale in a spinning motion as a result of the moving surfaces of the belts. Crop materials tend to slough off the bale as it rotates and to accumulate as residue or trash in various pockets or regions of entrapment defined by the belts as they are looped around guide rolls and drive rolls which span the baling chamber of the machine.
One area of particular problem in a variable chamber baler (in which the chamber progressively increases in size during bale formation) is located adjacent the front end of the machine where a front stretch of the belts leading from the baling chamber is looped under a drive roll located adjacent the front of the entrance to the baling chamber. From that location the belts are then directed either forwardly and thence upwardly to other guide rolls or essentially immediately upwardly to higher rolls so as to form a generally V-shaped region of entrapment above the lower drive roll. This trapping region changes shape as the bale grows within the baling chamber and actually becomes progressively more confined as the latter stages of the bale growth are reached, due to the fact that as the bale enlarges, the span of belts engaging the front side of the bale is deflected forwardly from its initial position located more rearward in the machine. This has a tendency to pack and compress the trapped residue within the region and make it even more difficult to expel.
Because the collected residue can lead to malfunction of the baler in certain severe conditions, prior devices and belt arrangements have been utilized in an effort to solve the problem. One such arrangement is disclosed in Viaud U.S. Pat. No. 4,399,746 titled "Staggered Rolls and Belts for Round Baler" in which the belts adjacent the front of the machine are entrained around guide rolls in such a manner that escape openings are presented adjacent the bottom of the entrapping region to allow the materials to expel themselves from the machine.
Another approach is to utilize rotating, pronged discs or plates which typically project into the spaces between adjacent belts of the baler to physically engage the accumulated residue and to forcibly expel it through the spaces between the belts. One such arrangement is disclosed in Herring U.S. Pat. No. 4,890,449 titled "Attachment for Round Hay Baler". See also, U.S. Pat. No. 4,336,750 issued to White, et al., and titled "Stray Crop Buildup Expeller for Rotary Balers".
While rotary cleanout discs generally perform adequately for their intended purpose, in some cases they may damage the belts. This condition may arise where one or more of the belts goes slack during the baling operation and climbs onto the rotating disc. The points or projections on the disc may then tear into the belt, or at least stress it to such an extent that the belt must be prematurely replaced.